Fusible electric switch unit



March 1956 H. J. HAMMERLY FUSIBLE ELECTRIC SWITCH UNIT Filed Aug. 18

Inventor": Herman J. Hammer-Lg, 1 W

H is Attorney.

United States PatentO 2,738,399 FUSIBLE ELECTRIC SWITCH UNIT Herman I.Hammerly, Plainville, Conn., assignor to General Electric Company, acorporation of New York Application August 18, 1953, Serial No. 374,925

4 Claims. (Cl. 200-163) My invention relates to improved fusibleelectric switch units.

It is common practice to use a bridging contact of U-shape in fusibledisconnect switches of large rating. These structures are usuallysomewhat complex and expensive and not well suited to smaller switcheswhich are used, for example, in housing wiring systems. The presentinvention has for an important object the provision of a simplifiedsupport and actuator for the bridging contact and also an improved andsimplified support for the stationary contacts and terminals of a switchunit of this type.

It is another object of my invention to provide a novel contactstructure which insures a quick make upon contact closure without thecomplication involved in a snap action activating mechanism.

Further objects and advantages will become apparent as the followingdescription proceeds, reference being had to the accompanying drawing,and its scope will be pointed out in the appended claims. In thedrawing, Fig. 1 is a front elevational view of an enclosed fusibleswitch unit embodying my invention; Fig. 2 is an enlarged elevationalview of the unit of Fig. 1 with the cover removed; Fig. 3 is an enlargedsectional view taken along the line 3-3 of Fig. 1; Fig. 4 is an explodedview in perspective showing the various parts of the switch unit; Fig. 5is a sectional view taken along the line 55 of Fig. 2 and showing theswitch parts in open position and Fig. 6 is a similar view showing theswitch parts in closed position.

Referring now to the drawing, I have shown my invention embodied in afusible switch unit mounted in a general purpose metal enclosing case 1having a hinged cover 2 provided with an elongated slot 3 to receive theoperating handle 4 of the switch unit. The fuse block and switch bodyare, in the preferred form of my invention illustrated, provided by asingle molded body of insulating material 5 secured against the back ofthe case 1 by means of a lug 6 formed integrally with the back of thecase and by a screw 7 having threaded engagement with the case. Sincethe base is recessed from both the front and back to receive conductingparts of the switch unit, it is insulated from the case 1 by means of asheet 8 of insulating material interposed between the base 5 and thecase 1.

The particular embodiment of my invention illustrated is adapted to fuseand switch two conductors. In order to facilitate its application to twosingle phase circuits or one two phase three wire circuit, a neutral orground bus is provided by the conducting strap 9. The remainder of thestructure, with the exception of the operating handle, is duplicatedabout a vertical center line as viewed in Fig. 2 and in the interests ofsimplifying the description only one half will be described.

The base 5 is molded to provide a novel supporting and housing structurefor the terminals and contacts of the switch unit. As illustrated thebase is recessed from both the front and back to provide supportingwalls 10 and 10 extending generally parallel to the back of the casingand intermediate the front and back of the insulating base 5. The wall10 is also accessible from the upper edge of the base and provides asupport for a U-shaped conducting member 11 to provide one of the lineterminals of the device as well as one of the stationary contacts 12 ofthe switch. The U-shaped member is slipped over the wall 10 and held inposition by a binding screw 13 and also is adapted for connection to anexternal circuit conductor. The wall 10 is integral with a wall portion14 extending toward the front of the base 5 and providing a guide forone arm of the U-shaped movable or bridging contact 15.

In a similar manner the wall 10' supports the shell and center terminals16 and 17 respectively which are adapted to receive a plug fuse and aterminal strap 18 which terminates in a curved stationary switch contact19. As best illustrated in Figs. 5 and 6 the inturned flange at thebottom of the shell terminal is clamped against the wall 10' by thecenter terminal which is in the form of a rivet 17 and washer 17. Therivet also secures the strip 18 to the back of the wall 10. The centercontact is insulated from the shell contact by a suitable insulatingwasher 17 The second terminal 16 of the switch device is provided by aconducting strap terminating at its inner end in a washer 16" clampedbetween the insulating washer 1t) and the inturned flange of the shellterminal 16.

A wall section 20 extends from the inner end of the wall 10 toward thefront of the casing and partially encloses the shell terminal and alsoprovides a guiding surface for the other leg of the U-shaped contact 15.Inter mediate between the stationary contacts 12 and 19 is an insulatingbarrier 21 which extends substantially beyond the plane of thestationary contacts to provide an elongated path for any are between thestationary contacts thus facilitating the interruption of current uponwithdrawal of the U-shaped bridging contact. As illustrated in Fig. 4the wall 21 is supported from side walls 23 and 24 which cooperate withthe walls 14 and 20 to provide a substantially closed rectangularswitching chamber.

As illustrated in Figs. 5 and 6, the walls 14 and 20 are recessed at 25to receive the ribs 26 which are pressed out of the opposed arms of theU-shaped switching member. These ribs are spaced from the contactportions of the arms and serve to deflect the arms inwardly away fromthe stationary contacts until the movable contact is fully inserted atwhich time the projections 26 drop into the recesses 25 allowing theopposed arms of the movable contact to engage the stationary contacts 12and 19 with a quick make action independently of the speed of movementof the handle 4. As illustrated the walls 14 and 20 preferably convergea little toward the contacts 12 and 19 to gradually move the arms of themovable contact 15 together as the contact is moved toward closedposition.

The U-shaped member is operated between the positions shown in Figs. 5and 6 by means of a toggle type operating member 4 supported from theintegral bearings 27 formed on the base 5 by means of a pivot pin 28. Anintegral hub 29 extends from the side of the switch operating member 4at a point spaced from the pin 28 and the U-shaped contact is mounted onthis hub. The opposed legs of the contact are indented as shown at 30 sothat it substantially surrounds the hub 29. It is apparent that as thetoggle member is moved about the pin 28 the movable contact is insertedbetween and withdrawn from the stationary contacts 12 and 19.

It will be seen that each of the bridging contacts 15 is extremelysimple in construction, being formed of straight strip metal stockdeformed only in a direction generally transverse to its major fiatsurfaces, so that it may be readily fabricated as by rolling, stamping,bending, etc. 'The contacts are readily assembled, moreover, by merelysliding them onto the hubs 29' and then inserting them in the switchingchambers before the handle shaft 28 is assembled. The shaft 28, ,when inplace, serves to. retainthebridging contacts.15.in operativepositionsince. it limits the possible movement of the handle 4 torotational movement, and in either. extreme. position,-as

indicated in Figures ,5 and -6, the contacts15 do not fully Moreover, aswill,

emerge from the switching-chamber. be seen by reference to Figures .2and 5, although the bridgingcontact 15 is still partially placed withinthe recess in the open position, the ribs 26 areuplainly visibleswitchas shown in Figs. 5 and 6 with an indentation32 formed inthe cover.These openings 31 aresuitable to receive a padlock or other locking.means which engages the indentation 32 to restrain the operating memberfrom movement. 4

While there has been shown and described a particular embodiment of theinvention, it will be obvious to those skilled in the art that changesand modifications may be made without departing fromv the invention, andthat it is intended by the appended claims to cover all such changes andmodifications as. fall within the truespirit and scope of the invention.

What 1 claim as new and desire to secure by Letters 'iatent of theUnited States is: V

1. An electric switch unit comprising a pair of stationary contacts, abase of insulatingv material supporting said contacts in spaced andinsulated relation, a U-shaped contact, an operating member pivoted onsaid base, and a hubsupported on said operating metnber extendingbetween the opposed arms of saidU-shaped contact, said.

generally cylindrical hub projecting therefrom generally a parallel tosaid axis and eccentric th'ereto, a. generally U-shaped'resilientmovable bridging contact, means guiding said movable contact forreciprocatingmovement along a substantially rectilinear path into andout of engagement with said stationary contacts, said U-shaped resilientcontact being formed of relatively thin strip material, the sides ofsaid contact being indented adjacent the bight thereof toward each otherto provide a generally cylindrical bearing whereby said contact isadapted to be pivotally supported on said hub to be reciprocated therebyalong said path into and out of engagement with saidstationary contacts.

3. An electricswitch unit comprising-a base of insulating materialhaving anelongated generally rectangular recess therein, two relativelystationary contacts carried by said base and having contact'portionsextending into said recess, a manually operable handle member pivotallysupported on an axis on said base and having a generally cylindrical hubprojecting therefrom generally parallel to said axis and eccentricthereto; a generally U-shaped resilient movable bridging contact formed'of relatively thin strip material, the sides ofsaidtcontact beingindented adjacent the bight thereof toward. each other to provide ahollow generally cylindrical bearing, the said hub extending into saidbearing to-provide'a' pivotal connection between said handle and saidcontacts,

and said contact extending within saidrecess, the walls of said recessserving to guide said contact for reciprocating movement into and out ofengagement with said stationary, contacts.

4. The electric switch unit as set forth in claim 3, said handle memberbeing movable about its pivotal axis between .an on position wherein:said U-shaped contact is in engagement with said stationary contacts,and-an 1 off position wherein said U.-shaped contact is out ofengagement with said stationary contacts, said U-shaped contact having adeformed portion adjacent an end there of remote from said bight, saiddeformed portion being visible from the front of said. switchwhen saidhandle member is in said oil position, and saidcontact having at least aportion thereof remaining within said recess when said handle is in saidoff position.

References Cited in the tile of this patent UNITED STATES PATENTS2,253,968 Cook .Aug.. 26; 1941 2,492,101 Landmeier Dec. 20, 19492,494,315 Rowe Jan. 10, 1950

